The inventors have developed an optical switch/switch activator for use in hazardous and non-hazardous environments, and more particularly to a float activated optical switch, where the switch activator is an obstacle that can interrupt a beam of light (or pass a beam of light, depending on the orientation of the activator in the float body). See U.S. Pat. No. 7,234,830, hereby incorporated by reference. Improvements to the base optical device are contained in PCT/US2007/70122, filed May 31, 2007, hereby incorporated by reference.
The earlier inventions require two light guides (such as fiber optic cables), one connected to a source of light, the other connected to a light detector. Each light guide has a distal end positioned in a activator, where the two distal ends are separated by a gap but can be optically aligned. An optically opaque means to interrupt the beam of light is positioned in the gap, and in one position, blocks the light path (optical path absent) and in another position, does not obstruct the light path (optical path present). Hence the device operates as a switch upon detection of the presence or absence of light by the light receiver. As disclosed in the PCT/US2007/70122 application, one embodiment has the means to interrupt (such as a rollable ball, or slidable cylinder or slug) positioned in an ampoule containing a fluid to reduce “switch flutter.” As also disclosed in the PCT application, the two distal ends of the cable may be substantially parallel, with a reflective surface positioned above the distal ends, thereby creating an optical path from the light source cable to the light receiver cable by bouncing light (light may be visible light, infrared light, ultraviolet light (such as black lights, etc.), off the reflective surface. See FIG. 11 of the PCT. However, the configuration shown in that FIG. 11 is not sufficiently compact to create a compact activator for use in a small bodied switch, such as a small diameter float switch.